Extracorporeal blood pump, heart-lung machine, method for operating an extracorporeal blood pump, and method for operating a heart-lung machine

The present invention is a U.S. National Stage under 35 USC 371 patent application, claiming priority to Serial No. PCT/DE2017/000376, filed on 8 Nov. 2017; which claims priority of DE 10 2017 000 843.4, filed on 31 Jan. 2017, the entirety of both of which are incorporated herein by reference.

The invention relates to an extracorporeal blood pump, a heart-lung machine, a method for operating an extracorporeal blood pump and a method for operating a heart-lung machine.

The heart, as the central organ of the circulatory system, is a hollow muscle with two chambers which promotes the blood circulation by contraction and relaxation. From its left chamber (left ventricle), the blood is pumped through the arteries of the greater circulation to the capillaries of the body periphery. Through the veins, the blood reaches the right ventricle. From there, it is transported by the lung's arteries into the lung (lesser circulation) and returns to the left ventricle via the lung's veins. The lesser circulation is located in the chest.

In case of heart conditions, patients may reach a situation in which an artificial circulatory support is the only possible and therefore life-maintaining therapy.

Heart-lung machines can replace the vital circulatory functions of blood transport and gas exchange, for example during heart surgery. In derivation therefrom, heart-lung machines can also be employed for stabilizing patients with cardiac or pulmonary insufficiency over days. This process is called extracorporeal membrane oxygenation (ECMO) or extracorporeal life support (ECLS). During this process, blood is removed via cannulae which are introduced by minimally invasive methods, is then processed and returned to the patient.

WO 2009/024308 A1 discloses an electric linear drive, in particular for a pump system of an artificial heart.

EP 2 523 702 A1 discloses an assembly having a blood pump and a gas exchanger for extracorporeal membrane oxygenation.

The invention is based on the task of providing the state of the art with an improvement or an alternative.

In a first aspect of the invention, the task is solved by an extracorporeal blood pump for the aspiration and displacement of blood, the blood pump having two blood chambers and a mechanical driving unit, wherein the driving unit is arranged between the blood chambers, wherein a blood chamber has a membrane, a blood input channel and a blood output channel, wherein the blood output channels of both blood chambers are interconnected.

Some terminology will be explained in the following:

First, it is explicitly pointed out that within the framework of the present patent application, indefinite articles and numerals such as “one”, “two” etc. are normally to be understood as indicating a minimum, that is, “at least one . . . ”, “at least two . . . ” etc., unless it becomes explicitly clear from the context or is obvious to the person skilled in the art or technically inevitable that only “exactly one . . . ”, “exactly two . . . ” etc. can be intended.

A “blood pump”, which is frequently also called “artificial heart”, is a device which assumes or supports the function of the heart and is adapted to maintain the body circulation. In particular, a blood pump can be used for support in the context of a surgery, especially for temporarily assuming the function of the heart or for supporting the heart (peri-operatively), for assuming the function of the heart or for supporting it after a surgery (post-operatively) or for other purposes, that is, not in connection with a surgery within the framework of an intervention.

An “extracorporeal blood pump” is employed outside the body.

A “blood chamber” is a component of a blood pump which is adapted to be traversed by the designated blood flow. A blood chamber is provided with a “membrane”.

A “membrane” is a component of a blood pump as well as a component of a blood chamber and is adapted to alter its position and thus the volume of the blood chamber, and in doing so the designated blood stream is aspirated when the blood chamber volume is increased and the blood stream is displaced when the blood chamber volume is reduced. In particular, the “membrane” is adapted to alter its position such that a blood chamber only has approximately 10% or less of its maximum volume left, without this leading to impairments of the material behaviour of the blood chamber or of the membrane.

A “driving unit”, in particular a “mechanical driving unit”, is a constructive unit which drives a blood pump by transformation of energy.

A “blood input channel” is a channel through which the designated blood stream of an operating blood pump flows into an individual blood chamber.

A “blood output channel” is a channel through which the designated blood stream of an operating blood pump flows out from an individual blood chamber.

The state of the art until now has provided for predominantly employing rotatory pumps for supporting the functioning of the heart or for assuming the function of the heart. However, rotatory pumps can mechanically apply a relatively high level of shear stress to the blood due to their structural shape.

In the practical operation of rotatory pumps, an aspiration of canulae at the input end of the rotatory pump can frequently occur. The pressure/flow characteristics of rotatory pumps can inherently increase the aspiration pressure and can also further increase the shear stress on the blood or even cause cavitation of the blood, whereby a damaging of blood damage can be caused.

Alternatively, membrane pumps are employed in the state of the art.

In deviation from this, a specific construction of a membrane pump is proposed which has two blood chambers and a mechanical driving unit, wherein the driving unit is arranged between the blood chambers, wherein a blood chamber has a membrane, a blood input channel and a blood output channel, wherein the blood output channels of both blood chambers are interconnected.

Specifically, among other construction varieties, it is conceivable that both blood chambers have the same nominal volume.

With a suitable design of the blood pump, undercuts and dead water zones in the area traversed by the designated blood stream will be avoided.

Advantageously, with the aspect of the invention introduced here, the blood-leading side of the blood pump can be designed such that the blood can be protected as much as possible.

In this way, it can advantageously be achieved that the forces acting on the blood are kept relatively low and all areas of the blood pump are always washed out from the blood.

Thus, advantageously, damage of the blood cells and blood clogging can be prevented.

Advantageously, in this manner, a particularly energy-efficient blood pump can be constructed which protects the blood as much as possible and which can make the designated blood stream flow back into the body through a canula.

Preferably, the blood input channels of both blood chambers are interconnected.

In a suitable embodiment, both blood input channels are interconnected in a Y-arrangement such that the designated blood stream can be distributed over both blood chambers.

Advantageously, it can be achieved in this manner that blood is collected from the body with only one canula and that the designated blood stream is pressed in the blood pump in a very gentile blood protecting manner.

Optionally, a connecting area of the blood output channels has a backflow check valve.

Some terminology will be explained in the following:

A “connecting area” is an area where the designated partial streams of the blood from both blood chambers are reconnected.

A “backflow check valve” is a component adapted to be traversed with a minor loss of pressure in one direction of the flow and with a large loss of pressure in the opposite direction of the flow. In particular, the loss of pressure in the backflow direction is so large that a backflow can be prevented. Preferably, a backflow check valve is a stop for a designated blood stream in one direction of flow whereas the designated blood stream can pass through the backflow check valve unchecked or nearly unchecked in the opposite direction of flow. It can be said that a backflow check valve exhibits the properties of an adjustable shutter which is opened or closed in dependence on the designated direction of the flow.

It is specifically conceivable, among others, that the blood output channels converge in a connecting area from both sides, similar to a Y arrangement.

Thus, with a suitable design, it is achieved that when a designated blood stream is output, backflow of the blood into the other blood chamber is prevented.

In a preferred embodiment, the backflow check valve is designed so as to be well passed by the designated blood stream on both sides, whereby the backflow check valve is washed out well by the blood.

Advantageously, it can be achieved in this manner that the blood pump has a high energy efficiency.

In addition, it can be advantageously achieved that the backflow check valve and the connecting area are washed out well by a designated blood stream, and thus the formation of thrombi can be hindered.

Furthermore, it can advantageously be achieved that during the aspiration, blood can reach the blood chamber via the blood outlet channel.

Preferably, the driving unit has a gas inlet and a gas outlet as well as a pressure chamber, wherein the pressure chamber is separated from a blood chamber by a membrane, wherein the driving unit is in operative connection to the position of the membrane.

Some terminology will be explained in the following:

A “gas inlet” is an inlet for a gaseous fluid. The gas inlet is traversed by a designated gas flow such that gas flows into the driving unit.

A “gas outlet” is an outlet for a gaseous fluid. The gas outlet is traversed by a designated gas flow such that gas flows out of the driving unit.

A “pressure chamber” is a chamber adapted to be traversed by a designated gas flow. A pressure chamber has an “effective area”. The “effective area” is adapted to alter its position which can help to transform energy. In particular, an “effective area” can be a membrane separating a blood chamber from a pressure chamber.

Thus, it is concretely conceivable, for instance, to operate the blood pump with gas which releases energy into the blood stream in the driving unit.

The gas flow can be made available by a supply unit in a suitable manner.

In a suitable embodiment, a pressure chamber is arranged adjacent to a blood chamber. Thereby, the pressure chamber and the blood chamber are merely separated by the membrane.

In this way, the driving unit can be in operative connection to the position of the membrane.